And buzz word is the polar vortex what is that. What's an upper level well it started it up in the polls and McCain southward so underneath this upper low is where you have the court -- you can kind of see the shape of the here. You see the clouds here in the Dakotas and in -- comes around in that counterclockwise fashion. And it's this upper low that have all the Arctic air there's also some lake effect of course falling and we'll get to that in the second between -- be measuring the snow. Down -- in the lakes in feet. Over the next couple of days but underneath this upper low is it called -- you can kind of see the shape of -- with publisher take a look at this now. With the -- the Arctic air over you you're not going anywhere today Chicago Minneapolis Saint Louis Kansas City often think. Well the sun's out we're doing the day temperatures are going to be rising. That's not the case fifteen below right now in Chicago. Eighteen below in Minneapolis below zero ride along interstate seventy is well Kansas City Saint Louis Indianapolis is a level below. After -- snowstorm yesterday in this cold and if you -- figure out what's got to know losing each word here in fact. Still -- New York City 47 degrees forty in Washington DC. Malaysia had a lot of -- -- single numbers and Detroit Detroit you'll be below zero. By the time we get the 6 or 7 o'clock tonight seventeen in Pittsburgh and again this cold is spreading east. And it's also spreading south. Temperature still in the eighties in Miami but in the sixties and -- noticed that -- the Montgomery. All below freezing even the Big Easy right now is going to be below freezing so this is widespread cold there. Which means we're gonna see lots of record lows tonight from Atlanta toward Charlotte Washington DC Philadelphia Chicago we'll have a second night. Where we're going to be breaking records in fact fifteen below right now -- too far away from tonight's record low so this is going to be. A large area of record lows as we go through over the next -- for hours. And again as I mentioned with that cold air going over the warm lakes you're going to get -- the lake effect now how cold is it going to feel tonight. Take a look at best below forty below from Minneapolis -- Detroit. Even Chicago Pittsburgh anywhere from thirty to 35 degrees below zero that's outscored appealed -- a field below zero New York City Washington be seen again. Cold air warm lakes we're -- be measuring the snow in feet in a couple of various jobs sell the buffalo. Although buffalo you're going to get your snow but in an area called the Tug -- plateau. East of lake Ontario we're gonna probably end up having. About fortified feet of snow over the next couple of days in fact if you're watching the radars and AccuWeather dot com -- and that -- like -- -- -- -- shooting out a stream of water. -- that stream water it's going to be a bandits now when -- gonna see snowfall rates of two to three inches. Per hour Arctic air is here coldest we've seen in about the twenty years --

This transcript has been automatically generated and may not be 100% accurate.

{"id":21436073,"title":"Freezing Temperatures: Polar Vortex Explained","duration":"3:00","description":"AccuWeather's Bernie Rayno describes the arctic air making its way south.","section":"US","mediaType":"Default"}